﻿using System;
public class Rect
{
    public double Width { get; set; }
    public double Height { get; set; }
    public Rect(double width, double height)
    {
        Width = width;
        Height = height;
    }
    public Rect() : this(10, 10) { }
    public double Area()
    {
        return Width * Height;
    }
    public double Perimeter()
    {
        return 2 * (Width + Height);
    }
}
public class PlainRect : Rect
{
    public double StartX { get; set; }
    public double StartY { get; set; }

    public PlainRect(double startX, double startY, double width, double height)
        : base(width, height)
    {
        StartX = startX;
        StartY = startY;
    }

    public PlainRect() : this(0, 0, 0, 0) { }
    public bool IsInside(double x, double y)
    {
        bool inXRange = x >= StartX && x <= StartX + Width;
        bool inYRange = y >= StartY - Height && y <= StartY;
        return inXRange && inYRange;
    }
}
class Program
{
    static void Main(string[] args)
    {
        PlainRect rect = new PlainRect(10, 10, 20, 10);
        Console.WriteLine($"矩形面积: {rect.Area()}");
        Console.WriteLine($"矩形周长: {rect.Perimeter()}");
        double testX = 25.5;
        double testY = 13;
        bool isInside = rect.IsInside(testX, testY);
        Console.WriteLine($"点({testX}, {testY}){(isInside ? "在" : "不在")}矩形内部");
        Console.ReadLine();
    }
}
